please i need solutions Q3 and Q4,Q5

Q3: Consider the insertion sort in decreasing order: 1. Give a real word example of requires sorting. 2. What is the best scenario for this algorithm? 3. What is the worst scenario for this algorithm? 4. Prove that maximum possible number of execution of instruction 6 for an array of length n is n(n+1)/2 Q4: write a recursive pseudo-code to calculate i=0ni2 Q5: Use the iteration method to show that n is an exact power of 2(n=2k) the solution of the following recurrence is T(n)=nlogn. T(n)=2ifn=2and2T(2n)+nforn=2k,ifk>1